* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

a {
    text-decoration: none;
    color: #000;
}

li {
    list-style: none;
}

.w {
    width: 1200px;
    margin: 0 auto;
}

.main {
    background-color: pink;
    font-family: Arial, sans-serif;
}

/* 头部开始 */
.header {
    height: 50px;
    background-color: red;
}

/* 头部结束 */

/* 侧边栏开始 */
.siderbar {
    float: left;
    width: 100px;
    height: 500px;
    background-color: blue;
}

ul li {
    width: 100%;
    background-color: palevioletred;
    padding: 10px 0;
    text-align: center;
    cursor: pointer;
}

ul li:hover {
    background-color: gainsboro;
}

/* 侧边栏结束 */

/* 内容区开始 */
.content {
    float: left;
    width: 1100px;
    height: 500px;
    background-color: green;
}

.btn1-content,
.btn2-content,
.btn3-content,
.btn4-content {
    /* width: 100px; */
    height: 50px;
    background-color: yellow;
    text-align: center;
    line-height: 50px;
    margin: 10px;
}

/* 内容区结束 */